Thanks for your comment. I looked at what you said about Hottentots and this is what he said:

"There was very clearly, before 1939, what Sir Charles Snow has called “Two Societies” in our one civilization. This meant that most men lived in an ignorance of science almost as great as that of a Hottentot and almost equally great among highly educated professors of literature at Harvard, Oxford, and Princeton. It also meant that scientists were quite out of touch with the major realities of the world in which they lived."

It wasn't used in an offensive way, he was using that nomadic tribal people who were not plugged into western education systems, comparing them to how much the common people in the western educated world knew about the details of science pre-1939. The word Hottentot is no longer used but he wrote the book in the early 1960s when it was not seen as offensive, he was using it as a word that described a nomadic pre-modern culture who would by their lifestyle be unaware of what was going on in the modern western world.

I also searched for how much and in what context he used the word "backward." He tells us what he means by backward:

"backward or undeveloped"

He uses it a lot, almost always for areas within western countries, for parts of the world before they were completely modernized. For example:

"The German example was copied in Japan and in Italy, and, on a different basis, in France, with the result that the Common Market area enjoyed a burst of economic expansion and prosperity which began to transform western European life and to raise its countries to a new level of mobility and affluence such as they had never known before. One result of this was the development of what had been backward areas within these countries, most notably in southern Italy, where the boom caught on by 1960."